The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Vic woman to face trial over boat death

A tour operator will stand trial for the death of a man who was killed during a dolphin-spotting trip off the Victorian coast.

Torie Sandra Mackinnon, 30, was reversing her boat as one of her passengers, 60-year-old Paul McVeigh, jumped into the water and was struck by the vessel's propellers near Portsea in December 2013.

Magistrate Peter Reardon said on Thursday there appeared to be a distinct lack of on-board safety and training on Mackinnon's Moonraker Dolphin Swims, and the passengers should have been behind safety gates.

"Safety instructions were not given any prominence but were part of a package," he said.

During the committal hearing in the Melbourne Magistrates Court, defence barrister Constantine Heliotis argued Mr McVeigh's death was a tragic accident, not a criminal one.

He said Mackinnon could not be in control of everyone on the vessel and had delegated responsibility to a deckhand.

Safety warnings were given and repeated, and common sense should tell passengers not to get off a moving boat, Mr Heliotis said.